I'd probably go a bit lighter green than that, just because I wouldn't be into a dark room...green's grouse though, because no matter how un-pink you are, you'll get given pink and purple stuff, and that goes well with green!

Fairy lights instead of a lamp too? That could be cool - actually, IKEA have hanging lights, like leaves.

My best friend had a medieval themed room as a teenager, red velvet curtains and lots of red velvet, with fake ivy over the walls, wrought iron and fake spiderwebs! Looked grouse.

That colour green goes well for an enchanted garden kind of theme actually! Faeries, and dragonflies, and butterflies...ohhh a girl to dress in awesome vintage flower material...*drools*